This is our fifth year recommending window air conditioners (originally as Wirecutter, now as Sweethome), and my third year on this beat, personally. We’ve put in nearly 100 total hours of research and spent more than 30 hours doing real-world testing, along with more than 1,000 hours of being cooled off by the models we’ve recommended. Our expert sources include a representative for the Environmental Protection Agency, which administers the Energy Star program, as well as Max Sherman, an HVAC+R (heating, ventilation, air conditioning, and refrigeration) engineer who works as a staff senior scientist at Lawrence Berkeley National Laboratory.

All of our air conditioner picks are available in several Btu (British thermal units) configurations. To figure out which is for you, measure the square footage of the room you need to cool, then look at this Energy Star chart to find the appropriate cooling capacity, as measured in Btu. For most people, it’s as simple as that. You won’t always be able to find an AC with the perfect Btu rating, so you might have to round up. For example, nobody makes a 9,000-Btu window AC, so a 10,000-Btu window AC is the next-best option in that case.

The LG LW8016ER is the window AC you should probably get, especially if it’s for an office, den, or other room where you won’t be sleeping. Though for some people, it’ll be fine in the bedroom, too. It’s priced fairly and is widely available, so you’ll have no trouble running out and grabbing it for a decent price on short notice—for instance, in the middle of a heat wave, like when you’re probably reading this article. It’s quieter and hums along at a lower pitch compared with others in this price range, making it easier on the ears. And though AC controls aren’t rocket science, this one offers a greater level of flexibility in total than most of its competitors, covering all the little details—from the fan’s directional controls and outdoor-air vent to the dehumidifier mode and removable drain plug.

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Most air conditioners are loud, but the LW8016ER is the least-worst of the $250ish window ACs that we’ve been able to test because it’s a bit quieter overall and sounds lower-pitched. At its absolute loudest, with the compressor on and the fan at full speed, we measured it running at 66 dBC (that is the C-weighted decibel scale). At the slowest fan setting and with the compressor on we measured about 62 dBC. The lowest fan-only (no-cool) setting is about 60 dBC. Relative to our runner-up pick, that’s only about 1 dBC quieter in cooling modes, and 3 dBC quieter in fan-only mode. However, most people would probably think that the LW8016ER sounds quieter than its price peers. This is because it runs at lower frequencies. We also didn’t notice any mid- or high-frequency spikes, which tend to stand out in your awareness as hard-to-ignore whining or whooshing. That all adds up to an AC that’s easier on the ears than its competitors—even if it’s still a little louder than most of us would like.

As far as nitpicks go, the LW8016ER had the most cumbersome installation of all the window units we tested, but really, it’s not that much tougher to install than other window ACs—they’re all heavy and don’t vary much in this respect. The 8,000-Btu unit we tested weighed 58 pounds, which is heavy but not outrageous for a window AC. Compared with the others, it’s deeper and heavier toward the back, so it’s the trickiest to lift and maneuver onto the windowsill. Another nitpicky, moderately annoying detail: The side curtains screw in, whereas those of most other units slide in. That said, you’ll have to deal with installation only once each spring and once each fall, so it’s not a huge deal. Enlist a buddy, use a support bracket, and installation will be fine.

If you’re installing an air conditioner in your bedroom, or you just value peace and quiet in any other room, treat yourself to the (relatively) hushed performance of the Haier Serenity Series ESAQ408P. It usually costs about 25 percent to 35 percent more than our main pick or runner-up, but it gets quieter than any other AC we tested. You’ll sleep better all summer.

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At its lowest fan setting (called “quiet” here) and with the cooling mode turned on, the Serenity Series runs at 56 dBC. That’s 6 dBC quieter than our main pick, which is a substantial difference, and 1 dBC quieter than the next-quietest AC, the Friedrich Chill. (The Chill is quieter than the Serenity Series at faster fan speeds, but our assumption is that you’ll tend to sleep with the lowest fan speed on, so the Serenity Series has the edge in that regard.) We didn’t register any annoying frequency spikes, either. It’s not silent, but if you can fall asleep while you watch TV, you can fall asleep near this air conditioner.

However, unlike most models we recommend in this guide, the Serenity Series is available in only two sizes: 8,000 Btu (ESAQ408P) and 6,500 Btu (ESAQ406P). If you need a quiet AC for a larger space, we recommend grabbing a Friedrich Chill unit of the appropriate size.

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A portable pick: best for basements or horizontal sliding windowsHaier HPN12XCM

If you have the option of installing a window (or wall) unit, a portable air conditioner is usually the wrong choice. Portables cost more and they never cool a room as effectively or efficiently. They have to fight an uphill battle, trying to remove hot air from an area but inevitably reradiating some of that heat back into the same space. Worse yet, they still need to vent out of a window (they just don’t rely on the window for structural support). That’s because unlike most other kinds of ACs, portables sit entirely inside your home.

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But in a few cases, a portable AC is actually the best (or only) option, and using one is more comfortable than not having an air conditioner. The most obvious case where a portable is a good option is for people who live in a basement apartment, where the windows are usually too short to install a window AC and the air is too humid to get comfy with just a fan or DIY cooler. Also, certain kinds of full-size windows (like bay windows) won’t work with other kinds of ACs, so a portable would be the only choice in that situation as well.

If your situation falls into the above categories, we recommend the Haier HPN12XCM. Many portable ACs are pretty similar to each other, but the HPN12XCM has a few small advantages over its competitors. Most important, it’s a bit quieter than most units, and is one of the easier models to install and uninstall and roll from room to room, even on carpet. We found its controls and remote to be simple and intuitive, and the machine is less of an eyesore than most others. Its price is consistently on the low end of the spectrum, and several major retailers carry this unit. And as far as we can tell, it’s one of the better models in terms of making a room comfortable.

These picks may have been updated. To see the current recommendations, please read Sweethome’s guides to the best window and portable air conditioners.